Luminal grafts and methods of making and using the same

1. A luminal graft comprising a generally tubular element configured for nerve cells to grow therethrough, the luminal graft comprising:

at least one sheet of biological tissue having elastin fibers and collagen fibers, with the elastin fibers being a dominant component thereof; and

a plurality of microchannels formed on a surface of the at least one sheet of biological tissue, each of the microchannels extending longitudinally between a first end and a second end of the at least one sheet of biological tissue and configured to provide intraluminal structural guidance to nerve cells proliferating therethrough;

wherein the biological tissue comprises pulmonary ligament tissue or visceral pleura tissue.

2. The luminal graft of claim 1 , further comprising a plurality of biodegradable microspheres affixed to the surface of the at least one sheet of biological tissue and positioned in rows extending longitudinally between the first end and the second end of the at least one sheet of biological tissue, wherein the rows of microspheres define side portions of the plurality of microchannels.

3. The luminal graft of claim 2 , wherein each of the biodegradable microspheres encapsulates a substance and when the biodegradable microsphere degrades, the substance is released therefrom.

4. The luminal graft of claim 3 , wherein the substance comprises a neurotrophic factor.

5. The luminal graft of claim 2 , wherein the plurality of biodegradable microspheres further comprises a first set of biodegradable microspheres encapsulating a first neurotrophic factor and a second set of biodegradable microspheres encapsulating a second neurotrophic factor.

6. The luminal graft of claim 5 , wherein the first neurotrophic factor comprises NGF and the second neurotrophic factor comprises NT-3.

7. The luminal graft of claim 2 , wherein the plurality of biodegradable microspheres further comprises a first set of biodegradable microspheres that have a first rate of degradation and a second set of biodegradable microspheres that have a second rate of degradation; wherein the first rate of degradation is faster than the second rate of degradation.

8. The luminal graft of claim 1 , wherein the at least one sheet of biological tissue is arranged to form cylinder comprising a plurality of internal layers, each layer comprising a plurality of biodegradable microspheres positioned in rows extending longitudinally between the first end and the second end of the sheet, wherein the rows of microspheres define side portions of the plurality of microchannels.

9. A luminal graft comprising a generally tubular element configured for nerve cells to grow therethrough, the luminal graft comprising:

at least one sheet of biological tissue having elastin fibers and collagen fibers, with the elastin fibers being a dominant component thereof; and

a plurality of microchannels formed on a surface of the at least one sheet of biological tissue, each of the microchannels extending longitudinally between a first end and a second end of the at least one sheet of biological tissue and configured to provide intraluminal structural guidance to nerve cells proliferating therethrough; and

a plurality of biodegradable microspheres affixed to the surface of the at least one sheet of biological tissue and positioned in rows extending longitudinally between the first end and the second end of the at least one sheet of biological tissue, wherein the rows of microspheres define side portions of the plurality of microchannels;

wherein the plurality of biodegradable microspheres further comprises a first set of biodegradable micro spheres that have a first rate of degradation and a second set of biodegradable microspheres that have a second rate of degradation; wherein the first rate of degradation is faster than the second rate of degradation; and

wherein the first set of biodegradable micro spheres is positioned at or near the first and second ends of the at least one sheet of biological tissue and the second set of biodegradable micro spheres is positioned in a middle portion of the at least one sheet of biological tissue.

10. A method for performing a luminal grafting procedure, the method comprising the step of:

implanting the luminal graft of claim 1 within a mammalian body at a location of a proximal nerve stump and a distal nerve stump.

11. The method of claim 10 , further comprising the steps of:

releasing a first set of neurotrophic factors from a first set of the microspheres to facilitate nerve proliferation at or near the first end and the second end of the at least one sheet of biological tissue; and

releasing a second set of neurotrophic factors from a second set of the microspheres to facilitate nerve proliferation in a middle portion of the at least one sheet of biological tissue.

12. The method of claim 11 , wherein the step of releasing a first set of neurotrophic factors occurs at a first time and the step of releasing a second set of neurotrophic factors occurs at a second time, the second time occurring after the first time.